code: def on_sample_end(self, *, worker, samples, **kwargs):
      print(
          "mean. distance from origin={}".format(np.mean(self.deltas))
      )
      self.deltas = []
  
imports: from collections import deque
  import gymnasium
  import minigrid
  import numpy
  import sys
  import unittest
  import ray
  from ray import air, tune
  from ray.rllib.algorithms.callbacks import DefaultCallbacks
  import ray.rllib.algorithms.ppo
  from ray.rllib.utils.test_utils import check_learning_achieved, framework_iterator
  from ray.rllib.utils.numpy import one_hot
  from ray.tune import register_env
label_desc: Use image node_id 3 for calling the MyCallBack obj's underlying member method code with example usage: obj.on_sample_end() without return types